[PATCH] mac80211: suppress kernel warning message

[Yibo Zhao <yiboz@codeaurora.org>]

In multiple SSID cases, it takes time to prepare every AP interface
to be ready in initializing phase. If a sta already knows everything it
needs to join one of the APs and sends authentication to the AP which
is not fully prepared at this point of time, AP's channel context
could be NULL. As a result, warning message occurs.

Even worse, if the AP is under attack via tools such as MDK3 and massive
authentication requests are received in a very short time, console will
be hung due to kernel warning messages.

WARN_ON_ONCE() could be a better way for indicating warning messages
without duplicate messages to flood the console.

Signed-off-by: Zhi Chen <zhichen@codeaurora.org>
Signed-off-by: Yibo Zhao <yiboz@codeaurora.org>
---
 net/mac80211/ieee80211_i.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h
index a8af4aa..682d0ab 100644
--- a/net/mac80211/ieee80211_i.h
+++ b/net/mac80211/ieee80211_i.h
@@ -1435,7 +1435,7 @@ struct ieee80211_local {
 	rcu_read_lock();
 	chanctx_conf = rcu_dereference(sdata->vif.chanctx_conf);
 
-	if (WARN_ON(!chanctx_conf)) {
+	if (WARN_ON_ONCE(!chanctx_conf)) {
 		rcu_read_unlock();
 		return NULL;
 	}
-- 
1.9.1